In research, manufacture, and electrical equipment operation, it is oftentimes necessary that accurate measurement of electrical quantities, such as current, voltage, and/or resistance, be made. The basic methods for current, voltage, and impedance or resistance measurement have heretofore been developed and are well-known, as are various devices for effecting such measurements. Included among such devices are indicating instruments, such as D'Arsonval instruments to measure direct currents and voltages, moveable-iron-vane instruments for measuring alternating currents and voltages, and electronic volt-ohm-ammeters for measuring voltage, current, and resistance, for example. While such devices have proved to be acceptable for some desired measurements, none of the devices herefore known and/or utilized have proved to be successful for at least some desired measurements, and more particularly in making measurements where high impedance is necessary in the probe unit of the measuring device to measure voltage.